Research-on-research studies or methodological studies are primary research

Journal of Clinical Epidemiology has recently published a study of Faggion and Diaz Cavero [1], in which the authors presented types of primary and secondary research. According to the article, secondary research includes two categories —overviews and systematic reviews, whereas primary research includes three categories: human research (e.g., clinical trials, cohort, case series, and so on), animal research, and in vitro research [1]. Although the aim of the study was obviously not to classify all types of research conducted no wadays, this figure glaringly omits classifying the exact type of study that the Faggion and Diaz Cavero [1] have reported in their article.
Source: Journal of Clinical Epidemiology - Category: Epidemiology Authors: Tags: Letter to the Editor Source Type: research